A Theoretical Study of Substituted Dioxiranes: Difluorodioxirane, Fluorofluoroxydioxirane, (Fluoroimino) dioxirane, and Hydrazodioxirane

摘要

Equilibrium geometries and harmonic vibrational frequencies of three substituted dioxiranes, CO_2FOF, CO_2NF, and CO_2(NH))2, which have not been previously investigated, are reported. Results are based on second-order M#THETA#ller-Plesset (MP2) and quadratic configuration interaction through single and double excitation (QCISD) calculations using 6-31G(d) and 6-311G(d,p) basis sets. Molecular geometric characteristics, vibrational frequencies, dipole moments, as well as local atomic charges, are compared with those of known dioxiranes (CO_2H_2, CO_2F_2, CO_2N_2, CO_4). It is found that bond lengths and angles of the dioxirane ring are sensitive to the electropositivity of the central carbon. Hydrazodioxirane, CO_2(NH))2, is found to be a high-energy density molecule; whereas fluorofluoroxydioxirane (CO_2FOF) may be of further interest as a powerful oxidizer. Equilibrium geometries and vibrational frequencies of the previously uncharacterized energetically low-lying 1~3B_1 and 1~3B_2 triplet states of CO_2F_2 and the ground state of its cation, CO_2F_2~+(1~2A_2), are predicted and analyzed.